Extract logic into lib.rs

src/bin/id3-image-embed.rs

@@ -1,6 +1,8 @@
 use std::env;
 use std::process;
 
+use id3_image::embed_image;
+
 fn main() {
     let args: Vec<_> = env::args().collect();
 
@@ -12,35 +14,8 @@ fn main() {
     let music_filename = args[1].clone();
     let image_filename = args[2].clone();
 
-    let mut tag = match id3::Tag::read_from_path(&music_filename) {
-        Ok(t) => t,
-        Err(e) => {
-            eprintln!("Error reading music file {}: {}", music_filename, e);
-            process::exit(1);
-        },
-    };
-
-    let image = match image::open(&image_filename) {
-        Ok(i) => i,
-        Err(e) => {
-            eprintln!("Error reading image {}: {}", image_filename, e);
-            process::exit(1);
-        },
-    };
-
-    let mut encoded_image_bytes = Vec::new();
-    // Unwrap: Writing to a Vec should always succeed;
-    image.write_to(&mut encoded_image_bytes, image::ImageOutputFormat::JPEG(90)).unwrap();
-
-    tag.add_picture(id3::frame::Picture {
-        mime_type: "image/jpeg".to_string(),
-        picture_type: id3::frame::PictureType::Other,
-        description: String::new(),
-        data: encoded_image_bytes,
-    });
-
-    if let Err(e) = tag.write_to_path(music_filename, id3::Version::Id3v23) {
-        eprintln!("Error writing image to file: {}", e);
+    if let Err(e) = embed_image(&music_filename, &image_filename) {
+        eprintln!("{}", e);
         process::exit(1);
     }
 }

src/bin/id3-image-extract.rs

@@ -1,6 +1,8 @@
 use std::env;
 use std::process;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
+
+use id3_image::extract_image;
 
 fn main() {
     let args: Vec<_> = env::args().collect();
@@ -13,27 +15,9 @@ fn main() {
     let music_filename = args[1].clone();
     let image_filename = args.get(2).cloned().unwrap_or_else(|| replace_extension(&music_filename, "jpg"));
 
-    let tag = match id3::Tag::read_from_path(&music_filename) {
-        Ok(t) => t,
-        Err(e) => {
-            eprintln!("Error reading music file {}: {}", music_filename, e);
+    if let Err(e) = extract_image(&music_filename, &image_filename) {
+        eprintln!("{}", e);
         process::exit(1);
-        },
-    };
-
-    let first_picture = tag.pictures().next();
-
-    if let Some(p) = first_picture {
-        match image::load_from_memory(&p.data) {
-            Ok(image) => {
-                image.save(&image_filename);
-                println!("{}", image_filename);
-            },
-            Err(e) => {
-                eprintln!("Couldn't load image: {}", e);
-                process::exit(1);
-            }
-        };
     }
 }
 

src/lib.rs

@@ -0,0 +1,44 @@
+use std::error::Error;
+
+pub fn embed_image(music_filename: &str, image_filename: &str) -> Result<(), Box<Error>> {
+    let mut tag = id3::Tag::read_from_path(&music_filename).
+        map_err(|e| format!("Error reading music file {}: {}", music_filename, e))?;
+
+    let image = image::open(&image_filename).
+        map_err(|e| format!("Error reading image {}: {}", image_filename, e))?;
+
+    let mut encoded_image_bytes = Vec::new();
+    // Unwrap: Writing to a Vec should always succeed;
+    image.write_to(&mut encoded_image_bytes, image::ImageOutputFormat::JPEG(90)).unwrap();
+
+    tag.add_picture(id3::frame::Picture {
+        mime_type: "image/jpeg".to_string(),
+        picture_type: id3::frame::PictureType::Other,
+        description: String::new(),
+        data: encoded_image_bytes,
+    });
+
+    tag.write_to_path(music_filename, id3::Version::Id3v23).
+        map_err(|e| format!("Error writing image to file: {}", e))?;
+
+    Ok(())
+}
+
+pub fn extract_image(music_filename: &str, image_filename: &str) -> Result<(), Box<Error>> {
+    let tag = id3::Tag::read_from_path(&music_filename).
+        map_err(|e| format!("Error reading music file {}: {}", music_filename, e))?;
+
+    let first_picture = tag.pictures().next();
+
+    if let Some(p) = first_picture {
+        match image::load_from_memory(&p.data) {
+            Ok(image) => {
+                image.save(&image_filename);
+                println!("{}", image_filename);
+            },
+            Err(e) => return Err(format!("Couldn't load image: {}", e).into()),
+        };
+    }
+
+    Ok(())
+}